What is a Plane?

A Plane is an alternate reality. There are (for theoretical purposes) millions of planes all functioning at the same time, each without knowledge of any other. By this I mean the plane itself. The creatures that exist on a plane (or travel between planes) are an exception. Not all planes are the same; some are nearly impossible to survive in, while others are more habitable. The terms Plane and Realm are interchangeable for this writeup. They are arranged into an official CosmologySchematicDiagram similar to the one below (coming from the Manual):

Yes, there is a grand scheme that was invented to explain the order of the planes. There is one major plane, that everyone should be familiar with- the Material Plane. This is what humans call home. Spawning off of the Material Plane is the Plane of Shadows, the Astral Plane, and the Ethereal Plane. Then, from them spawns the inner and outer planes. They are the controlling forces of the Material Plane. Off of all of these planes are Demiplanes. Demiplanes are simply planes created to match a storyline that a Dungeon Master has created, and do not follow the conventional rules of any standard plane listed below. Demiplanes usually have one or more obscure properties that distinguish them from the standard planes, and are rarely used for more than one or two campaigns. Here is a little more detail on each of the planes:

The Material Planes-This is the collection of the planes that make up what the average adventurer would usually encounter. They are the planes that the D&D rules were made to function successfully under, and mimic an Earth-like environment. In certain multi-plane adventures, they will serve as the "homebase" plane.

The shape of the Plane of Shadows is meaningless, but what matters is the indisputable fact that each and every shadow is connected from the Material Plane to other alternate planes. Since the Plane of Shadows only connects a Material Planes to each of its other variations, none of the other planes in the cosmologies have shadows. Like vampires, you never see your shadow anywhere but on a Material Plane. Also, some have truly harnessed the power of the Shadow Plane, and can just step into the shadow of an object (no matter how small), instantly transporting them onto the Shadow Plane. (This idea was employed by Marvel Comics in the character Cloak, and was an odd coincidence. Marvel invented Cloak in 1980, before the book was published, but the idea of being able to sink into shadows also came out in the Manual of the Planes. Ironic? For more, see GlowingFish's writeup under Cloak and Dagger)

Quick delve into the realm of personal conjecture: Based on the above facts, that each shadow connects to the Shadow Plane, then there must be a duplicate shadow of every one in the any given version of the Material Plane on every other. This is why I say "alternate Material Plane" and "other versions of the Material Plane", because they must all be the same. In order to have the Plane of Shadows work correctly, there must be exact copies of each shadow in each other alternate plane. How different can they be?

Let's say you have a cube in front of you on a table, with a light source that points at it from an angle. That cube must cast a shadow, if there is only one light source in the room.

Let's pretend the second cube is the sister to the first one, but this one is on an alternate Material Plane. Here we see the shadow has changed shape, for now it must pass the top edge of the book, the back of the book, and what remains of the table. For now, omit the shadow of the book. These are both examples of the same shadow, so if someone were to try to jump through the Plane of Shadows from the shadow of cube A to the shadow of cube B, it could be done. They are the same shadow (being that they are attached to the cube), so no matter what form they take, they are tied together. This is how difference can exist between material planes. It does not matter how a set of items are arranged, they just must have sister copies on each other version of the Material Plane.
(This "Quick Delve" is my idea/opinion, and is open for debate. )

The Ethereal Plane- The Ethereal Plane is not actually a completely unique plane. It is merely a world, superimposed on top of the Material Plane. Anyone in the Ethereal plane sees what is going on in the Material plane, and can affect it in certain ways. However, someone on the Material Plane has absolutely no clue about the Ethereal plane or its inhabitants. One analogy that can be made is to use a Holodeck, made famous by the Star Trektelevision show. In a holodeck, humans walked around in a world projected by a computer. They could walk through anything (as you can in the Ethereal Plane), and could separate themselves and observe in the third person when necessary, as you always do in the Ethereal Plane. The Ethereal Plane has its own creature selection, that differs greatly from any found on the other planes. They are called celestials, and are nearly humanoid in their general appearance.

Elemental Plane of Air- The Plane of Air is has no solid ground. It is the easiest to survive of the planes, mostly because it presents few hazards as a direct result of the environment (not counting the monsters that may inhabit it). In this plane, there is no specific "down" for gravity to pull you. You determine your own direction of travel, and float that way. Newton's law applies- "objects at rest tend to stay at rest."Inanimate objects do not move unless forced externally. The Plane of Air is inhabited by many types of djinni, as well as ice, dust and air mephits. As its name implies, the plane is dominated by air elementals. Also, some remote corners of the plane are home to ash elementals, dust elementals, and hail elementals. The native language of the Plane of Air is Auran, "a breathy, leisurely tongue that sounds like slow exhalation" (Grubb 68).

Elemental Plane of Fire-The Fire Elemental Plane is an infinitely 2-dimensional realm, covered in a sea of magma and liquid flames. Occasionally, a mountain of molten lava can be found. Not much can survive here other than the fire elementals, and therefore it is rarely used in gameplay. The fire elementals feed off each other (symbiotically, not predatorially) to survive. Though not intended as one, the plane is often used as a pseudo-transitive plane between the Nine Hells and the City of Brass.

Elemental Plane of Earth-A realm of solid soil and rock. There is no surface; the soil stretches out infinitely. This can lead to major problems when entering from another plane, because the pressure can crush an unprepared traveler and entomb him permanently. "The Plane of Earth is not necessarily hostile, but more of uncaring. It is unconcerned about the life that inhabits it, what it does, or how it travels" (Grubb 71). The realm has a heavier gravity than the Material Planes, and therefore movement is impeded. The plane is dominated by earth and stone elementals, as well as some mephits of varying types. "The native tongue of the Elemental Plane of Earth is Terran, a deep rumbling tongue that vibrates through the listener like a tremor" (Grubb 71).

Elemental Plane of Water- The Plane of Water is like a fishtank, only there is no surface, no walls, and no floor. Lighting is ambient, and not from any particular direction. The gravity is very similar to the Plane of Air, but the effects of forces on an object are dampened by the water. Throughout the plane, tides push and pull the adventurers at random. The Plane of Water is inhabited by djinni, mephits, as well as a multitude of other sea-dwelling creatures. Any waterbreathing creature can make a home in this realm. (Exceptions- crabs, whales, dolphins, lobsters, or anything else that requires air or a seafloor to survive.)

Negative Energy Plane-This is a plane much like the Plane of Shadows, only much more hostile to the adventurer. It is dark, sinister, and a permanent void of all life, death, and soul. The realm consumes the traveler, drawing your life force out of you until there is not enough left to survive. Travelers can rarely survive this barren land for more than a few minutes; even then they need extremely strong reinforced shielding to withstand the sheer power of the plane. Very few creatures can make a home here because the land tugs at their life so harshly. Those that do live on the Negative Energy Plane are mostly pure evil, those without soul, life, or positive energy. There is no unified language that inhabitants speak, since most of them are too self absorbed or hermit-like to be social to outsiders. They are either hermits or hunters...most often in search of tasty adventurers. This plane is different from all of the previous ones because it has regions of varying intensity. There are "major," "minor," and "transitional" areas, each with their own attributes. The different intensities can be likened to barometric pressure, and how it appears higher in areas, and lower in others.

Figure IV: Barometric Pressure vs. Energy Intensity Scale
Similarly, there are no definite boundaries between the major and the transitional regions, or the minor and the transitional areas. The majors have a stronger force of negative energy than the transitionals do, and therefore are much harder to pass through. The minor areas are actually closer to positively charged than they are to the majornegative areas. Note that it is extremely rare for major and minor areas to be touching. Events like that produce random shifts in standard forces (i.e.- gravity, lighting, etc). These borders shift at whim, and follow no particular pattern. A traveler standing still may find the forces acting on him changing in intensity as often as every few seconds, while another traveler a few yards away may never notice anything (either because he is in one region, or the border is not shifting in either direction at any rapid rate of speed).

Positive Energy Plane- This is a plane that is the exact inverse of the negative energy plane in every aspect. This plane is the source of the positive energy used to power healing spells, destroy undead creatures, as well as good clerical magic. The plane is almost impossible to open your eyes in because of the brilliance it expels. As the negative plane was pitch black, devoid of light; the positive plane is radiant, full of light. The amount of raw energy in the plane makes it just as harsh and hostile as the Negative Energy Plane. The Positive Energy Plane is also devoid of life, because the positive force is so strong it can destroy even the most good-oriented creature. The Positive Energy Plane also has its major, minor, and transitive areas (see Negative Energy Plane above).

The Planes are not actually arranged in that manner, but a cube is a good visual analogy to represent which planes oppose or impose each other. The opposing planes are shown on opposite sides of the cube, and imposing planes are next to each other. It is rare to find an example of one element on its opposing plane, but common to find it on each of its imposing planes. (IE- You could find Earth regions in the Positive Energy Plane, Plane of Water, Negative Energy Plane, or the Plane of Fire. However, you won't find any on the Plane of Air, because Air and Earth are opposites.)

The Astral Plane- This is a complicated plane, and will result in a gargantuan writeup if I try to post it all. For a simple explanation, visit http://www.sundragonclan.com/maps/astralabyss.html .

The Outer Planes- "The outer planes are separate from the Material Plane, so travelers often reach them through the Astral Plane (by spells) and through interplanar portals. Individual subplanes can be separate from each other, or coterminous to each other, allowing movement between multiple planes" (Grubb 86). The Outer Planes are built on the structure of the known universe. They have representative planes that are specific to every version of life, death, creature, emotion, and mathematical/scientific sets. They are the extreme controllers of the demiplanes, Inner Planes, and the Material Planes. Their understood organization is in a ring, each major group linked to two others on its sides.

[Nidavellir]
[Muspelheim]
[Ysgard]
Ysgard
[Mithardir][Aquellor][Arvandor]ArboreaLimbo[Lymbia]
[Karasuthra][Brux][Krigala]BeastlandsPandemonium[Pandesmos][Cocytus][Phlegethon][Agathion]
[Thalasia][Belierin][Eronia][Amoria]ElysiumAbyss[Plain of Infinite Portals][][][](infinite # of planes)
[Shurock][Dothion]BytopiaCarceri[Orthrys][Cathrys][Minethys][Colothys][Porphatys]***
*[Venya][Mercuria][Lunia]CelestiaHades[Oinos][Niflheim][Pluton]
[Buxenous][Abellio]ArcadiaGhenna[Khalas][Chamada][Mungoth][Krangath]
[Mechania] MechanusNine Hells[Avernus][Dis][Minauros][Phlegethos]**
Acheron
[Avalas]
[Thuldanin]
[Tintibulus] -A.R.03
[Ocanthus]
*appended to the beginning of Celestia's list are the following:
[Chronias][Jovar][Mertion][Solania]...
**appended to the end of the Nine Hell's list are the following:
...[Stygia][Malbolge][Maladomini][Caina][Nessus][Avalas]
***appended to the end of the Carceri list are the following:
[Agathys]

Figure VI: The Organization of the Outer Planes

The outer planes are only traveled by the most skilled of sorcerers, or the unluckiest of adventurers. Before talking about each plane, let's discuss transportation. The most common form of transportation is through portals (either interplanar or intraplanar), or via advanced spellcasting by mages. However, there are other ways to get around in an old-style manner (via the wonderful feet):

In Elysium, a traveler can wade through the shimmering waters of the River Oceanus for an endless number of lifetimes, and never pass the same scenery twice. The river snakes through all of the planes of Elysium, but not on a set course like a river does on the Material Plane. The river is the main source of life for all of Elysium. It travels across Elysium from the outside in, toward the center of the ring of planes, then trails into the top layer of the Beastlands (Krigala), and dies out near the Arborean plains. (To get to Bytopia, a portal is needed)

In the Hells, the main form of travel is the River Styx. Most people know this river from mythology, but in Dungeons and Dragons, it takes on a whole different meaning. The River Styx flows from the top layers of Acheron, down through the Nine Hells, up Gehenna, down through the wastes of Hades, the depths of Carceri, the infinite Abyss, and ends up in the Pandemonium. (Now we wonder...if the Abyss is infinite, how long does it take the water to flow from the edge of Carceri to the beginning of Pandemonium? A strange glitch in the game, perhaps?)

In the Major Outer Planes, (the ones emboldened in the diagram above) each plane shares borders with the planes on its left and right. Skilled travelers that have been in the Outer Planes for a while often know of routes that allow for interplanar transportation via a simple footpath. The change in plane is not immediate; it happens gradually, and with each step the world looks more and more like the plane that is being entered. Eventually, the new plane takes over completely. (Grubb 86)

Much like the "RandomNode" link, there is an InfiniteStaircase that carves a path through each and every Outer Plane. The problem is figuring out where it is at any given time. In its infinity, it is completely random as to where a landing is this moment. Truly gifted spellcasters and the gods know its pattern, but they are not very interested in sharing it. An entrance usually appears as a mundanearch, somewhere in one of the Outer Planes. The arch is in a random location, so that may mean it's 400 miles below ground, or hovering 10 feet above. It could be anywhere. It changes often, but few people know the exact rate.

The Outlands can get you from anywhere in the Outer Planes to anywhere else. It lies in the center of the ring of Outer Planes, and connects to each first plane individually. (ie- the Outlands will connect from Orthys of Carceri to Amoria of Elysium, but not to Belierin of Elysium). The portals to and from the Outlands are well known, and often traveled by the less skilled adventurer, for they require little skill to use. In the harsher planes, basecamps are often built around those portals, so adventurers have a safe haven to enter and leave from.

On the Outer Planes, the inhabitants are often not interested in the bumbling travelers on quests to bother them, and cast them off with little more than the wave of a hand (or a claw or whatever passes for a hand for that creature). The inhabitants of these lands are a breed stronger than anything mortals have ever seen, and consist of the following:

Eternally Punished Souls:The cosmologies often like to think of the Outer Planes as a place to send mortals for punishment. Eternalpunishment. The nature of this punishment differs from campaign to campaign, but it is often just the soul of the creature/person in a repulsive and menacing form, out to get revenge on those who dare to pass. They are not to be bothered, for thousands of years in solitary confinement most likely has not made them any more cheery and welcoming to outsiders.

Quasi-Deity/Hero-Deity:These are people that are revered as gods, but lack any earth-moving capabilities. Therefore, they often resolve themselves to marking off their own corner of some obscure plane, and building their castle with brute force, not divine power. The upper echelons of Deities have no care for the Hero types, and they are often killed when a stronger deity decides to restyle his/her plane. The heroes often reach the plane they live on from a dead-end adventure, and may or may not be welcoming to a passing traveler- they may be happy to see a person that can take them home, or they may have become bitter toward the whole universe, and try to attack any adventurers they see.

Demideity:These are people that are not true gods, but of godly blood. They arise from the mixture of opposing deities' blood (ie- Life/death, fire/water, etc). Much like Hero-Deities, they lack any planulamorphic abilities, and must rely on their parents to do divine work for them. They are more respected than Hero-deities, due to their blood, but if pitted against each other, they would have the same odds. Demideities are almost always found on the same plane as their creating forces, seeing that it is a perfect safe haven for them to survive in. Demideities also must resort to building fortifications for their area of a plane by hand.

Lesser Deity:Now we get into the beginnings of planulamorphic abilities. The Lesser Deities have powers that can affect areas of a single plane. They can change physical characteristics, such as color, consistency, and events in a region. However, they cannot affect the alignment of that area of the plane (evil, good, neutral, etc).

Intermediate Deity:These gods are the same as lesser gods, only the intermediate gods have the ability to change the whole plane they reside on. They still cannot affect the alignment of the area, but have choice over color, consistency, and events in a region, etc.

Greater Deity:Greater Deities are the beings that all of the lower forms of immortals look up to. The Greater Deities have complete control over their plane; they can change anything they want to in the plane they are currently standing on. There is no restriction on their power within that plane, and a traveler will rarely pass more than one or two of them in their mortal lives.

Uber-Deity:Uber-Deities are not used in every campaign, but some DM's place them in order to achieve a certain, otherwise unattainable, affect. These are gods with unlimited power; able to alter other planes in any imaginable way. They are omnipotent, and have the power to create and/or destroy planes at will. They are to be feared. If one in 1,000 travelers comes across an Uber-Deity, they are extremely lucky.

(This completes my version of the Manual of the Planes.)

The official D&D3E Manual of the Planes, written by Jeff Grubb, Bruce R. Cordell, and David Noonan, covers all of the topics that are associated with alternate dimensions, broken up into 10 chapters. The chapters cover the following topics:

Nature of the Planes- A basic explanation of the concept of a plane. This includes how they are created, where to find them, what inhabits them, and other "cosmological and planar traits" (Grubb 4).

Connecting the Planes- If you intend to use coterminous alternate planes, then there must be some form of travel between them. This could be a teleport pad, or a one-way jump that the adventurers stumbled upon by mistake. The latter is not that complicated (and shows that the DM was somewhat lazy), so the better part of the chapter is on "how to move from plane to plane, and designing access points" (Grubb 4)

Characters and Magic- Now that there are multiple planes, characters have to be adapted to that type of adventuring. This section explains how to modify character's statistics, as well as the magical abilities they posses. Also, there now might be people that are exceptionally skilled at jumping between realms, so four new prestige classes were created for adventurers to aspire to.

The Material Plane- This is the chapter that delves into the details of the "plane that the characters most probably call home" (Grubb 4). It explores many of the intricacies of our realm that many average humans never notice (ie- the effects of gravity, how the sun affects the daily cycle of life, etc). This is a chapter more for those who are interested in altering this plane in a novel manner, as apposed to just sending the characters to another.

The Transitive Planes-These are not truly inhabitable planes. They are a form of transportation. In order to get from one plane to another, the adventurers must briefly pass through a transitive plane. However, that brief period gives the Dungeon Master (or DM) a chance to lay traps or plan devilish tricks on the adventurers.

The Inner Planes-"This chapter explores the raw elements and energies that make up your cosmology, or plane. They are the most hostile of the planes, and powerful elementals call them home" (Grubb 4).

The Outer Planes- Even more frightening than the Inner Planes, the Outer planes can only be survived by the deities (a.k.a.- gods). They are also home to extraplanar powers that affect the nature of all planes.

The Demiplanes-These are the planes that are not well defined, all the better for the Dungeon Master. Here is where the Dungeon Master can make up whatever rules he wants for their plane.

Monsters- Of course, the monsters that an adventuring group can find on this plane (the Material Plane) will be different from most other planes that they will go to. This chapter is selection of ideas to brainstorm on for monsters that can populate any plane.

Disclaimer: All information has been truncated out of respect for the authors and publishers. I do not want to delve into too much detail, or it defeats the point of buying the book for the rest of the D&D community. If you want to know more about this topic, msg me and I can speak to you about it. (Publishing it as a writeup will break copyright laws)